Apparatus for elementary analysis



June 24, 1969 KEICHIRO HOZUMI 3,451,779

APPARATUS FOR ELEMENTARY ANALYSIS I Filed Oct. 20. 1965 3 @U/L/NEAR' MOTION I MECHANISM II'T IIII I I I VII 2 VI Y III wi e l s l' 642 United States Patent U.S. Cl. 23-253 Claims ABSTRACT OF THE DISCLOSURE Apparatus for analyzing organic elements comprising a chamber for effecting combustion of organic samples, means for pumping the combustion products and a carrier gas to gas analyzing means and means for analyzing the constituents of the combustion gas. The means for analyzing the constituents of the combustion gas include a water detector, a carbon dioxide detector and a nitrogen detector.

This invention relates to apparatus for elementary analysis, and particularly to organic element analyzing apparatus which is capable of quickly analyzing a large amount of various organic samples into such elements as hydrogen, carbon and nitrogen.

It is known to burn an organic sample in a combustion tube into a gaseous body which is in turn forwarded to an analyzing system where various elements are successively detected. In such case, it is common practice to use a constant-volume mercury gas pipet. However, the mercury gas pipet involves such unavoidable disadvantages as fragile construction, complicated operation, diflicult control of the sample gas supplying speed and uneven dilution of the sample gas with a carrier gas.

The primary object of the invention is to provide new and improved means for forwarding the sample gas with a carrier gas toward the analyzing system, in which the above-mentioned disadvantages involved with use of mercury gas pipets can be avoided.

Apparatus for elementary analysis according to the invention comprises means for combustion of an organic sample, a piston pump for pumping the combustion gas with a carrier gas from said means for combustion and means for successively detecting constituents of the combustion gas pumped by the piston pump. Through the utilization of a piston pump there are obtained such many advantages as durable construction, simple operation, powerful supplying force, easy control of the sample gas supplying speed and uniform dilution of the sample gas with a carrier gas.

With use of a single pump mechanism, there is obtained a disadvantage that the supply of the sample gas to the analyzing system must be intermittently carried out because during the suction and exhaust operations of the pump, it is essential to halt exhaust and suction of the sample gas, respectively. This results in consumption of dead time.

Another object of the invention is, therefore, to provide new and improved means for continuously supplying the sample gas with a carrier gas to the analyzing system.

In a preferred embodiment of the invention, a pair of piston pump mechanisms for pumping the combustion gas with a carrier gas are provided. Such pair of piston pump mechanisms are in the opposite phases to each other and alternately communicated with means for combustion when they are in the suction stroke and also alternately communicated with the analyzing system when they are in the exhaust stroke. In this manner except when the pistons are at rest in the opposite stroke end positions, both suction and exhaust of the sample gas are always and concurrently effected with the result that a large amount of sample can be analyzed quickly and continuously.

A further object of the invention is to obtain such a pair of pump mechanisms as mentioned above in a simple construction.

This can be attained by forming a pair of piston chambers on the opposite sides of a piston within a single cylinder. It is obvious that such two pump chambers are always in the opposite phases to each other.

The other object and advantages of the invention will become apparent from the following detailed description in conjunction with the accompanying drawing which schematically illustrates the flow system of the apparatus according to the invention.

In the drawing, the reference numeral 1 designates a helium gas bomb and the reference numeral 2 designates an oxygen gas bomb. These two bombs 1 and 2 are at the end of the flow system of the apparatus according to the invention. The reference numerals 3 and 4 designate pressure control valves for maintaining at constant the helium gas pressure and the oxygen gas pressure, respectively. The reference numerals 5 and 6 designate flow control means for smoothing the helium gas flow and the oxygen gas flow, respectively. The reference numerals 7 and 8 designate flow meters. A solenoid valve 9 is inserted in the flow way 10 of oxygen gas. Oxygen gas is supplied through the solenoid valve 9 and a three-Way cock 11 to a combustion tube 12. A three-way solenoid valve 13 is inserted in the flow way 14 of helium gas. Helium gas is forwarded through the solenoid valve 13 either to the three-way cock 11 or to a four-way cock designated by the reference numeral 15.

The combustion tube 12 comprises an elongated tube having at its one end an opening 16 which is always left open to the atmosphere and an inlet 17 which is connected to the three-way cock 11. The inlet 17 is positioned near the opening 16. The tail end 18 of the combustion chamber 12 is communicated through a connecting pipe 19 to the four-way cock 15. The inner part of the tube 12 is packed with three-packing materials 20, 21 and 22 in that order. The packing material 20 which is packed in the innermost position is a reducing agent such as reduced copper, the packing material 21 immediately before the packing material 20 is composed of silver particles and the packing material 22 immediately before the packing material 21 is composed of a metal oxide for example, copper oxide. The space 23 above the packing material 22 is a combustion chamber for burning a sample. The reference numeral 24 indicates a platinum or quartz boat on which a sample is placed. The reference numeral 25 7 is a push rod for introducing the boat 24 with a sample from the opening 16 into the combustion chamber 23 of the tube 12. The reference numeral 26 indicates a combustion furnace surrounding the middle portion of the tube 12 substantially extending over the combustion chamber 23 and the copper oxide packing material 22 and maintaining that portion of the tube at a temperature within the range of about 800 C. to 900 C. The reference numeral 27 is a heating furnace surrounding the portion of the tube 12 at which the packing materials 20 and 21 are packed and maintaining that portion at a temperature within the range of about 500 C. to 550 C.

The four-way cock 15 is communicated through a connecting pipe to a pump mechanism. In the preferred em bodiment of the invention a pair of pump chambers are provided and the connecting pipe 19 can be selectively communicated through the four-way cock 15 to either one of the pump chambers. Although such pair of pump chambers may be separately constructed with the respective pistons, in the most preferable embodiment of the invention the two chambers 28 and 29 are formed within a single cylinder 30 on the opposite sides of a single piston 31 which is movable in the cylinder 30', as shown in the drawing. The two pump chambers 28 and 29 are communicated through the respective inlet passageways 32 and 33 to the four-way cock 15. The reference numerals 34 and 35 indicate the inlet solenoid valves for the pump chambers 28 and 29, respectively. The reciprocating move ment of the piston 31 is driven through a suitable rectilinear motion mechanism 36 by a motor 37. The reference numeral 38 indicates the piston rod transmitting the drive force from the rectilinear motion mechanism 36 to the piston 31. The stroke of the piston 31 is controlled and defined by a limit switch mechanism which may comprise an engaging member 39 fixed on the piston rod 38 and a pair of limit microswitches 40 and 41 which cooperate with the engaging member 39. When the engaging member 29 engages the limit microswitches 40 and 41, the piston 31 is in the left and right stroke end positions.

The two pump chambers 28 and 29 are communicated through the respective outlet passageways 42 and 43 to a three-way cock 44. The reference numerals 45 and 46 indicate the outlet solenoid valves for the pump chambers 28 and 29, respectively.

The three-way cock 44 is communicated through a connecting pipe 70 with a thermal conductivity cell 46 which is in turn connected by a U-shaped pipe 47 to another thermal conductivity cell 48. The U-shaped pipe 47 is packed with a packing material of a dehydrating agent such as magnesium perchlorate. The thermal conductivity cells 46 and 48 include platinum wire elements 49 and 50, respectively. Any difference in the thermal conductivity which may be produced between the two cells 49 and 50 is detected by a thermal conductivity bridge 51 including the platinum wire elements 49 and 50 and a galvanometer 52.

The thermal conductivity cell 48 is communicated by a connecting pipe 53 to a further conductivity cell 54 which is in turn connected by another U-shaped pipe 55 to a still further conductivity cell 56. The U-shaped pipe 55 is packed with a packing material of a decarbonating agent such as caustic soda particles. The thermal conductivity cells 54 and 56 include platinum wire elements 57 and 58, respectively. Any difference in thermal conductivity which may be produced between the two cells 54 and 56 is detected by a thermal conductivity bridge 59 including the platinum wire elements 57 and 58 and a galvanometer 60.

The thermal conductivity cell 56 is then connected by a connecting pipe 61 to still another thermal conductivity cell 62 which is in turn connected through a delay coil 63 to the last thermal conductivity cell 64. The delay coil 63 may be a metal coiled pipe having a long eifective length. The thermal conductivity cells 62 and 64 include platinum wire elements 65 and 66, respectively. Any difference in the thermal conductivity between the two cells 62 and 64 is detected by a thermal conductivity bridge 67 including the platinum wire elements 65 and 66 and a galvanometer 68. The last cell 66 is connected with a discharge pipe 69, the free end of which is left open to the atmosphere.

The element analysis with the above mentioned system according to the invention is carried out in such a manner as described in detail hereinbelow. The whole system may be automatically controlled by a timer (not shown in the drawing) according to a predetermined program.

When the timer dictates inroduction of a sample, the push rod 25 introduces the boat 24 with an organic sample to be analyzed into the combustion chamber 23 in the tube 12. The sample is burnt in the combustion chamber 23 at a temperature within the range of 800 C.-900 C. in the presence of oxygen gas and helium gas which are mixed at the cock 11 and then introduced through the inlet 17 into the combustion chamber 23, whereby thermal decomposition of the sample occurs. Carbon and hydrogen of the decomposed sample gas are oxidized into water and carbon dioxide, respectively, as the decomposed gas comes in contact with copper oxide packing material 22. The silver particle packing material 21 then absorbs sulfur and halogen included in the decomposed sample gas. Further the reduced copper packing material 20 abso'rbs an excess amount of oxygen gas supplied and reduces compounds of nitrogen with oxygen which might be produced.

The sample gas substantially consisting of water, carbon dioxide and nitrogen leaves the tail end 18 of the combustion tube 12 together with helium gas which serves as a carrier gas and is forwarded through the four-way cock 15 alternately to a pair of pump chambers 28 and 29. As soon as introduction of the sample is started, the piston 31 begins to move in the cylinder 30 at a slow speed from one stroke end position to the other stroke end position. This movement is imparted to the piston by means of the driving power of the motor 37 through a rectilinear motion mechanism 36 and the piston rod 38. When the piston 31 reaches the left or right stroke end position at the end of a predetermined interval of combustion time (e.g. four minutes), the engaging member 39 fixed on the piston rod 38 engages a microswitch 40 or 41 to switch off the motor 37, so that the piston 31 is stopped. During the rightward movement of the piston 31, the cock 15 communicates the connecting pipe 19 with the inlet passageway 32, and the inlet valve 34 of the pump chamber 28 and the outlet valve of pump chamber 29 are open while the outlet valve 45 of the chamber 28 and the inlet valve 35 of the chamber 29 are closed. During the leftward movement of the piston 31 the cock 15 communicates the connecting pipe 19 with the inlet passageway 33 and the inlet valve 35 of the chamber 29 and the outlet valve 45 of the chamber 28 are open while the outlet valve 46 of the chamber 29 and the inlet valve 34 of the chamber 28 are closed. In this manner, suction and exhaust of the sample gas are carried out simultaneously on the opposite sides of the piston 31.

The exhaust sample gas is forwarded through either outlet pasageway 42 or the outlet pasageway 43, the three-way cock 44 and the connecting pipe 70 to the first thermal conductivity cell 46. The mixed gas leaving the first cell 46 enters into the U-shaped pipe 47 to be dehydrated thereat and in turn passes through the second thermal conductivity cell 48. It will be understood that the gas introduced to the first cell 46 is a mixture of water, carbon dioxide, nitrogen and helium while the gas passing through the second thermal conductivity cell 48 is a mixture of carbon dioxide, nitrogen and helium, whereby the balance of the thermal conductivity bridge 51 is lost and the difference in the thermal conductivity is indicated by the galvanometer 52. In this manner any amount of hydrogen in the sample can be detected.

The gas mixture leaving the second thermal conductivity cell 48 passes through the third thermal conductivity cell 54 and in turn enters into another U-shaped pipe 55 at which carbon dioxide included in the gas mixture is removed thereform. Accordingly, the gas mixture leaving the U-shaped pipe 55 and entering into the fourth thermal conductivity cell 56 consists only of nitrogen and helium while the gas mixture passing through the third thermal conductivity cell '54 consists of carbon dioxide, nitrogen and helium. The difference in the thermal conductivity between the two cells 54 and 56 is detected by the thermal conductivity bridge 50 including the galvanometer 60. In this manner any amount of carbon in thesample can be detected.

The mixture of nitrogen and helium leaving the fourth thermal conductivity cell 56 passes through the fifth thermal conductivity cell 62 and in turn enters into the delay coil 63 to drive out pure helium gas previously introduced and existing therein toward the last thermal conductivity cell 64. The difference in the thermal conductivity between the last pair of cells 62 and 64 is detected by the thermal conductivity bridge 57 including a galvanometer 68. In this manner any amount of nitrogen in the sample can be detected. The gas leaving the last tlilermal conductivity cell 64 is discharged to the atmosp ere.

The detected signals at the three thermal conductivity bridges 51, 59 and 67 may be forwarded at fixed intervals of time to an amplifier, and after being amplified, is recorded in a suitable recorder.

The program for operating simultaneously the two pump chambers 28 and 29 in the different phases, respectively, is as follows:

First, suction of the combustion gas is effected at the pump chamber 28. At this time, at the pump chamber 29, a combustion gas is exhausted into the measuring or detecting stage. When suction of the combustion gas at the pump chamber 28 and exhaust of the combustion gas at the pump chamber 29 are finished, movement of the piston 31 is halted at that position for a while. Under this condition, the sample gases in the pump chamber 28 are intimately mixed up due to dilfusion, both solenoid valves 28 and 29 being closed. At the same time, scavenging action is effected in the pump chamber 29. The scavening may be effected in such a manner that with the solenoid valves 35 and 46 in open positions, helium gas from the bomb 1 is introduced through the three-way valve 13 and the four-way cock 15 into the pump chamber 24 and then forwarded to the detecting and measuring part including the thermal conductivity cells 46, 48, 54, 56, 62 and 64, the absorbing pipes 47 and 55 and the delay coil 63 to clean up them. During this operation the delay coil 63 is filled with pure helium gas. Concurrently therewith, helium gas is introduced through the cock 15 into the combustion tube 12 from its tail end 18. After cleaning the combustion tube, helium gas is discharged from the opening 16 to the atmosphere. Conversely, upon initiation of the movement of the piston 31 from the right stroke end position to the left stroke end position, the combustion gas in the pump chamber 28 is exhausted to the measuring part while suction of the combustion gas is effected in the pump chamber 29. When the piston 31 reaches the left stroke end position, its movement is stopped. At this state, diffusion is carried out in the pump chamber 29 for intimately mixing the combustion gas, the two solenoid valves being kept closed, while scavening is carried out in the pump chamber 28 with introduction of helium gas through the cocks l0 and 11, solenoid valves 34 and 45 being kept open, whereby the pump chamber 28 and the measuring and detecting system are cleaned.

By repeating the above mentioned operation, a large amount of organic sample can be quickly and continuously analized.

What I claim is:

1. Apparatus for analyzing organic elements comprismg:

means for effecting combustion of an organic sample;

a source of carrier gas;

a pair of piston pump mechanisms for pumping from said means for combustion the combustion gas and the carrier gas, each of said pair of piston pump mechanisms being in the phase opposite to that of the other;

means for mixing a carrier gas with the composition of gas of the organic sample;

means for alternately communicating each of said pair of piston pump mechanisms with said means for combustion so that the combustion gas may be pumped by that piston pump mechanism which is in the suction stroke;

means for successively detecting constituents of said combustion gas pumped by said piston pump mechanisms; and

means for alternately communicating said pair or piston pump mechanisms with said means for successively detecting constituents by that piston pump mechanism which is in the exhaust stroke.

2. Apparatus for analyzing organic elements comprismeans for effecting combustion of an organic sample;

a source of carrier gas;

a piston pump mechanism for pumping from said means for effecting combustion, the combustion gas and the carrier gas, said piston pump mechanism consisting of a cylinder and a piston movable in said cylinder and having a pair of piston chambers on the opposite sides of said piston, said chambers adapted to alternately be in a suction operation;

means for mixing the combustion gas and the carrier means for alternately communicating each of said pair of piston chambers with said means for combustion so that the combustion gas may be pumped by the pump chamber which is in the suction operation;

means for successively analyzing constituents of said combustion gas pumped by said piston pump mechanism; and

means for alternately communicating said pair of piston chambers with said means for successively analyzing constituents by the piston pump chamber which is in the exhaust operation.

. 3. Apparatus for analyzing organic elements comprismg:

means for effecting combustion of an organic sample;

a source of carrier gas;

a piston pump mechanism for pumping from said means for combustion the combustion gas and a carrier gas, said piston pump mechanism consisting of a cylinder and a piston movable in said cylinder and having a pair of piston chambers on the opposite sides of said piston, which chambers are adapted to alternately effect suction and exhaust chambers;

means for successively analyzing constituents of said combustion gas pumped by said piston pump mechanism;

means for communicating said pair of piston chambers alternately with said means for combustion when they are in the suction mode;

means for alternately communicating said pair of piston pump chambers with said means for successively analyzing constituents of said combustion gas when said piston pump chambers are in the exhaust mode; and

means for communicating said piston chambers directly with a carrier gas source and with said means for successively analyzing constituents of said combustion gas when said pump chambers are at the end of the exhaust mode.

4. Apparatus for analyzing organic elements as defined in claim 3, wherein said means for successively analyzing constituents of said combustion gas comprise means for absorbing water, means for absorbing carbon dioxide and a nitrogen detector, said nitrogen detector comprising a delay coil pipe having a long effective length, a pair of thermal conductivity cells on the opposite ends of said delay coil and means for detecting the difference in the thermal conductivity between said two thermal conductivity cells.

5. Apparatus for analyzing organic elements comprismg:

a carrier gas source;

an oxygen gas source;

a combustion tube having a combustion chamber therein, one end of said combustion tube being open to the atmosphere;

three kinds of packing materials located in the combustion tube for oxidizing elements of the thermally decomposed gas, for absorbing sulfur and halogens and for absorbing an excess amount of oxygen and reducing compounds of nitrogen with oxygen, respectively;

means for supplying a mixture of carrier gas and oxygen gas from said carrier gas source and oxygen gas source to said combustion chamber;

a piston pump having a cylinder, a piston arranged for reciprocation within the cylinder and a pair of pump chambers which are formed on the opposite sides of the piston within the cylinder;

means for alternately communicatng said pair of chambers to the interior of said combustion tube;

means for selectively communicating said pump chambers directly to said carrier gas source;

means for actuating said piston for reciprocating movement;

limit switch means for limiting the stroke of said piston;

a water detector which comprises a water absorbing a pair of thermal conductivity cells at the opposite ends of said water absorbing pipe;

means for detecting the diiference in the thermal conductivity between said pair of cells;

means for alternately communicating said pair of pump chambers to said water detector;

a carbon dioxide detector which is communicated with said water detector and which comprises a carbon dioxide absorbing pipe;

a pair of thermal conductivity cells at the opposite ends of said carbon dioxide absorbing pipe;

means for detecting the dilference in thermal conductivity between said pair of cells;

a nitrogen detector which is communicated with said carbon dioxide detector and which comprises a delay coil pipe;

a pair of thermal conductivity cells at the opposite ends of said delay coil pipe; and

means for detecting the difference in thermal conductivity between said two cells.

References Cited MORRIS O. WOLK, Primary Examiner.

20 R. E. SERWIN, Assistant Examiner.

US. Cl. X.R. 

